Electronic parts packaging structure and method of manufacturing the same

ABSTRACT

In an electronic parts packaging structure of the present invention constructed by stacking a plurality of sheet-like units in a thickness direction, each of the units includes a first insulating layer, wirings formed on one surface of the first insulating layer, a semiconductor chip (electronic parts) connected to the wirings, a second insulating layer formed on an one surface side of the first insulating layer to cover the semiconductor chip, and connecting portions (terminals and contact vias) for connecting electrically the wirings and wirings of other unit, wherein arrangement of the first insulating layer, the semiconductor chip, the wirings, and the second insulating layer is symmetrical between units adjacent in a thickness direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority of Japanese PatentApplication No. 2005-211938 filed on Jul. 21, 2005, and No. 2005-373859filed on Dec. 27, 2005, the entire contents of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic parts packaging structureand a method of manufacturing the same and, more particularly, anelectronic parts packaging structure having a package structure in whichelectronic parts such as a semiconductor device (chip), and the like aremounted in an inside of a wiring substrate to attain a reduction inthickness and a method of manufacturing the same.

2. Description of the Related Art

Improvements in the functions of the electronic parts are facilitatedrecently. The LSI (Large Scale Integrated Circuit) technology as the keytechnology makes progress steadily toward a higher speed and a largercapacity of the data transmission. Also, the LSI packaging technology isprogressing year by year, and a large number of LSIs can be mounted in anarrow space at a high density.

In reply to the request for the higher density, the multi-chip package(semiconductor device) in which a plurality of semiconductor chips arestacked and mounted three-dimensionally on the wiring substrate has beendeveloped. As an example, there is the semiconductor device having sucha structure that a plurality of semiconductor chips are mountedthree-dimensionally on the wiring substrate in a state that they areburied in the insulating film and a plurality of semiconductor chips areconnected mutually via via holes and wiring patterns formed in theinsulating film (Patent Literatures 1 to 5, for example).

-   [Patent Literature 1] Patent Application Publication (KOKAI)    2001-196525-   [Patent Literature 2] Patent Application Publication (KOKAI)    2001-177045-   [Patent Literature 3] Patent Application Publication (KOKAI)    2000-323645-   [Patent Literature 4] Patent Application Publication (KOKAI)    2005-217225-   [Patent Literature 5] Patent Application Publication (KOKAI)    2005-209689

Meanwhile, in case the insulating film for coating the semiconductorchip is formed of a resin, the semiconductor chips and the wiring (metalfilms), whose coefficients of thermal expansion are different from thatof the resin film, exist in the resin film. Therefore, the semiconductordevice is warped easily due to a thermal stress caused by a differencebetween these coefficients of thermal expansion when the resin film isthermally treated and formed. As a result, it is possible that suchdefects are produced that such warp interferes with handling of thesemiconductor device in post treatment, the reliability of connection isdecreased upon mounting the semiconductor device on the mountingsubstrate (mother board), etc.

In above Patent Literatures 1 to 5, the structure in which thesemiconductor chips are buried and mounted in the insulating film (resinfilm) are set forth respectively, nevertheless no consideration is givento the warp of the semiconductor device caused due to the above thermalstress.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an electronic partspackaging structure capable of increasing a mounting density much higherthan the prior art and preventing generation of a warp in such astructure that electronic parts are mounted while they are buried in aninsulating film, and a method of manufacturing the same.

An electronic parts packaging structure of the present inventionconstructed by stacking a plurality of sheet-like units in a thicknessdirection, each of the units includes a first insulating layer, a wiringformed on one surface of the first insulating layer, an electronic partsconnected to the wiring, a second insulating layer formed on an onesurface side of the first insulating layer to cover the electronicparts, and a connecting portion for connecting electrically the wiringand a wiring of other unit, wherein arrangement of the first insulatinglayer, the electronic parts, the wiring, and the second insulating layeris symmetrical between units adjacent in a thickness direction.

The electronic parts packaging structure of the present invention isconstructed by stacking the sheet-like units in which the electronicparts is buried respectively. Each unit is constructed by the firstinsulating layer, the wirings, the electronic parts such as thesemiconductor chip, or the like, the second insulating layer, andconnecting portions, and does not have a high strength supportingsubstrate (a thick substrate) serving as a core. Also, a total strengthcan be ensured by stacking a plurality of units. As a result, theelectronic parts packaging structure of the present invention achieves amuch higher mounting density of the electronic parts than the electronicparts packaging structure with the supporting substrate in the priorart.

Also, in the present invention, the arrangement of the first insulatinglayer, the electronic parts, the wirings, and the second insulatinglayer is symmetrical between units adjacent in a thickness direction.Therefore, even when a thermal stress is caused due to differences inthe coefficients of thermal expansion among the electronic parts, theinsulating layers, and the wirings (metal films), warping directions dueto the thermal stress come opposite in the units adjacent in thethickness direction and thus warps are cancelled mutually. As a result,it can be prevented that the warp is caused in the electronic partspackaging structure.

In one preferred mode of the present invention, the first insulatinglayer is formed of a solder resist. In the present invention, the firstinsulating layer is arranged on the outermost surface of the electronicparts packaging structure. Normally the insulating layer in which theelectronic parts is buried (the second insulating layer) is formed ofthe epoxy resin, or the like. In this case, commonly the solder resistis higher in strength than the epoxy resin. Therefore, when the firstinsulating layer arranged on the outermost surface is formed of thesolder resist, a strength of the electronic parts packaging structurecan be increased and generation of the defects such as damage, etc. canbe suppressed.

In case the electronic parts is the semiconductor chip, it is preferablethat the device forming surface of the semiconductor chip should beprotected by the protection film. In this case, if a coefficient ofthermal expansion of the protection film is adjusted to the midway of acoefficient of thermal expansion of the semiconductor chip and acoefficient of thermal expansion of the first insulating layer 22 bymixing silica, or the like with the protection film, a stress generateddue to a difference in the coefficient of thermal expansion between thesemiconductor chip and the first insulating layer can suppressed.

Also, a method of manufacturing an electronic parts packaging structureof the present invention, includes the steps of preparing a plurality ofsheet-like units each of which is constructed by a first insulatinglayer, a wiring formed on one surface of the first insulating layer, anelectronic parts connected to the wiring, a second insulating layerformed on an one surface side of the first insulating layer to cover theelectronic parts, and a connecting portion for connecting electricallythe wiring, and stacking mutually the units to arrange directions ofunit adjacent in a thickness direction alternately oppositely, andbonding the units such that electronic parts of respective units areelectrically connected mutually via connecting portions.

In the present invention, the units are bonded to arrange directions ofthe units adjacent in a thickness direction alternately oppositely.Therefore, the arrangement of the first insulating layer, the electronicparts, the wirings, and the second insulating layer is symmetricalbetween the units adjacent in the thickness direction. As a result, evenwhen a thermal stress due to the difference in the coefficient ofthermal expansion between the electronic parts and the insulating layerand the wirings (metal films) is generated, directions of the thermalstress come opposite in these units and thus the warp of the electronicparts packaging structure can be avoided.

The unit is manufactured, for example, via a first step of forming afirst insulating film made of an insulating resin on a substrate, asecond step of forming an opening by patterning the first insulatingfilm, a third step of forming a recess by etching the substrate exposedfrom the opening, a fourth step of forming a terminal by filling a metalin the opening, a fifth step of forming a wiring, which is connected tothe terminal, on the first insulating film, a sixth step of bonding anelectronic parts onto the wiring, a seventh step of forming a secondinsulating layer, which covers the electronic parts, on the firstinsulating film, an eighth step of forming a hole that reaches thewiring from an upper surface of the second insulating layer, a ninthstep of forming a contact via by filling a metal in the hole, and atenth step of removing the substrate.

Since the unit manufactured in this manner has no high strengthsupporting substrate (a thick substrate) serving as a core, theelectronic parts packaging structure of the present invention canachieve a much higher mounting density than the electronic partspackaging structure with the supporting substrate in the prior art.Also, in the method of the present invention, since the first insulatinglayer, the wirings, the electronic parts, the second insulating layer,and the like are supported by the substrate until the ninth step andthen the substrate is removed by executing the tenth step after twounits are bonded, for example, no hindrance to the handling in themanufacturing steps is caused.

In one preferred mode of the present invention, a third insulating layeris formed on a lower surface of the substrate in the first step, and thethird insulating layer is removed during a time from an end of the ninthstep to a start of the tenth step. It may be considered that, when theinsulating layer (the first insulating layer) is formed only on theupper surface of the substrate, the warp due to the difference of thecoefficient of the thermal expansion between the substrate and theinsulating layer is caused in the heat treatment such as the postbaking, or the like. As described above, if the insulating layer (thethird insulating layer) is also formed on the lower surface of thesubstrate, the direction in which the warp is caused comes opposite onand under the substrate and resultantly the warp can be suppressed.

Also, another method of manufacturing an electronic parts packagingstructure of the present invention, includes a step of forming aplurality of sheet-like units each of which is constructed by a firstinsulating layer, a wiring formed on one surface of the first insulatinglayer, an electronic parts connected to the wiring, and a secondinsulating layer formed on an one surface side of the first insulatinglayer to cover the electronic parts; a step of forming a stackedstructural body by stacking the plurality of units to arrange directionsof unit adjacent in a thickness direction alternately oppositely; a stepof forming a through hole, which passes through the first insulatinglayer, the wiring, and the second insulating layer of respective units,in the stacked structural body; and a step of forming a connectingportion, which connects electrically wirings of respective units, byfilling a conductor in the through hole.

In the present invention, the units are also bonded to arrangedirections of the units adjacent in a thickness direction alternatelyoppositely. Therefore, the arrangement of the first insulating layer,the electronic parts, the wirings, and the second insulating layer issymmetrical between the units adjacent in the thickness direction. As aresult, even when a thermal stress due to the difference in thecoefficient of thermal expansion between the electronic parts and theinsulating layer and the wirings (metal films) is generated, directionsof the thermal stress come opposite in these units and thus the warp ofthe electronic parts packaging structure can be avoided.

In one preferred mode of the present invention, the step of forming theunits includes a step of forming a first insulating layer made of aninsulating resin on a substrate, a step of forming a wiring on the firstinsulating layer, a step of bonding an electronic parts onto the wiring,and a step of forming a second insulating layer, which covers theelectronic parts, on the first insulating layer. Also, the stackedstructural body is formed by executing sequentially a pair unit formingstep of forming a pair unit by bonding two unit each having thesubstrate to oppose a surface on which the electronic parts is mountedto each other, a substrate removing step of removing the substrate fromthe pair unit, and a stacking step of stacking a plurality of pairunits.

In the present invention, the through holes are formed in the stackedstructural body to pass through the first insulating layer, the wiring,and the second insulating layer, and then the wirings of respectiveunits are connected electrically by filling the conductor in the throughholes. In this case, for example, the substrate is left in only thelowest unit, and then the connecting portions can be formed by formingthe through holes, which reaches the substrate from an upper surface ofthe stacked structural body, by means of a drill or a laser irradiation,and by depositing a conductor such as copper, or the like in the throughholes by means of a plating method. The substrate of the lowermost unitis removed after the connecting portions are formed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing an electronic parts packagingstructure according to a first embodiment of the present invention;

FIGS. 2A to 2O are sectional views showing a method of manufacturing anelectronic parts packaging structure according to the first embodimentof the present invention;

FIG. 3 is a sectional view showing a variation of the method ofmanufacturing the electronic parts packaging structure according to thefirst embodiment of the present invention;

FIG. 4 is a sectional view showing a method of manufacturing anelectronic parts packaging structure according to a second embodiment ofthe present invention;

FIG. 5 is a schematic plan view (general view) showing the method ofmanufacturing the electronic parts packaging structure according to thesecond embodiment of the present invention;

FIGS. 6A and 6B are sectional views showing a method of manufacturing anelectronic parts packaging structure according to a third embodiment ofthe present invention;

FIG. 7 is a sectional view showing an electronic parts packagingstructure according to a fourth embodiment of the present invention; and

FIGS. 8A and 8N are sectional views showing a method of manufacturingthe electronic parts packaging structure according to the fourthembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be explained with reference tothe accompanying drawings hereinafter.

(First Embodiment)

FIG. 1 is a sectional view showing an electronic parts packagingstructure according to a first embodiment of the present invention.

An electronic parts packaging structure (semiconductor device) 1 of thepresent embodiment has a structure that plural (four in FIG. 1)sheet(thin film)-like units 10 are stacked to put an insulating layer 11between them. Each unit 10 is constructed by a insulating resin layer(second insulating layer) 30, a semiconductor chip (electronic parts) 27buried in the insulating resin layer 30, a solder resist layer (firstinsulating layer) 22, wirings 26, terminals 24, and contact vias 31. Athickness of one unit 10 is almost 200 μm (almost 100 to 300 μm), forexample, and neighboring units 10 in the vertical direction (thicknessdirection) are electrically connected mutually via the terminals 24 orthe contact vias 31 (connecting portions).

The electronic parts packaging structure 1 of the present embodiment hasone feature that, as shown in FIG. 1, the neighboring units 10 in thevertical direction are arranged mutually in the opposite direction. Thatis, arrangement of the solder resist layer 22, the semiconductor chip27, the wirings 26, the terminals 24, the contact vias 31, etc. isvertically symmetrical between two units 10 adjacent in the verticaldirection.

One unit 10 is constructed by the insulating resin layer 30, thesemiconductor chip 27, the solder resist layer 22, the wirings 26, theterminals 24, and the contact vias 31, as described above. The solderresist layer 22 is stuck to one surface of the insulating resin layer30. The wirings 26 are formed on a surface of the solder resist layer 22of the insulating resin layer 30 side, and are connected electricallyvia connection terminals of the semiconductor chip 27 and bumps 28. Anunderfill (protection film) 29 is filled in a space between thesemiconductor chip 27 and the solder resist layer 22 to protect a deviceforming area of the semiconductor chip 27.

The terminals 24 are formed to pass through the solder resist layer 22,and are jointed to one surfaces of the wirings 26. Also, the contactvias 31 are buried in the insulating resin layer 30 and formed, and areconnected to other surfaces of the wirings 26.

As described above, in the electronic parts packaging structure 1 of thepresent embodiment, each unit 10 is constructed by the solder resistlayer 22, the semiconductor chip 27, the insulating resin layer 30, andthe like, and no high strength supporting substrate (in other words, athick substrate) serving as a core is provided. Also, a general strengthof the packaging structure can be ensured by stacking a plurality ofunits 10. As a result, the electronic parts packaging structure 1 of thepresent embodiment achieves such an effect that a mounting density canbe increased much higher than the electronic parts packaging structurewith the supporting substrate in the prior art.

Also, in the electronic parts packaging structure 1 of the presentembodiment, the solder resist layer 22, the semiconductor chip 27, thewirings 26, the terminals 24, the contact vias 31, and the like arearranged to be symmetrical to each other in the units 10 adjacentvertically. Therefore, even when a thermal stress is caused due todifferences in the coefficients of thermal expansion among thesemiconductor chip 27, the insulating resin layer 30, and the wirings(metal films) 26, warping directions due to the thermal stress comeopposite in the units 10 adjacent vertically. As a result, it can beprevented that the warp is caused in the electronic parts packagingstructure 1 because their thermal stress can be cancelled.

Also, in the electronic parts packaging structure 1 of the presentembodiment, an outermost surface is covered with the solder resist layer22 made of an acrylic-based resin or an epoxy-based resin. Normally thesolder resist layer 22 is higher in strength than the insulating resinlayer 30 made of an epoxy resin, or the like. For this reason, thepresent embodiment possesses such an advantage that a strength of theelectronic parts packaging structure can be increased rather than thecase where the insulating resin layer made of epoxy resin, or the likeis exposed from the outermost surface and that the electronic partspackaging structure is hard to break.

FIGS. 2A to 2O are sectional views showing a method of manufacturing anelectronic parts packaging structure according to the first embodimentof the present invention in order of steps. In this case, in FIGS. 2A to2O, only one unit forming area is shown to simplify the explanation, butactually a plurality of units 10 are formed simultaneously on a sheet ofsubstrate 21.

First, in first step (see FIG. 2A), the substrate 21 made of copper (Cu)and having a size of 300 mm×500 mm and a thickness of 0.1 mm, forexample, is prepared. Then, a photosensitive solder resist is coated onone surface of the substrate 21 by the screen printing method, and thusthe solder resist layer 22 of 20 to 30 μm thickness, for example, isformed. Then, the solder resist layer 22 is exposed via a predeterminedexposure mask (not shown). Then, opening portions 22 a from which asurface of the substrate 21 is exposed are formed by applying thedeveloping process to the solder resist layer 22. Then, the post bakingis applied at a temperature of 150 to 200° C., for example.

Here, the substrate 21 has a role as a supporting member to support thesolder resist layer 22, and the like and a role as a current feedinglayer at a time of the electroplating. Therefore, strength andconductivity are demanded of the substrate 21 to some extent. Also, itis necessary that the substrate 21 can be removed easily by the stepdescribed later. As the substrate 21, 42 Alloy (Fe—Ni alloy) plate, forexample, can be employed in addition to the copper plate mentionedabove. In this case, if the substrate 21 is too thick, a time requiredfor the later step to remove the substrate 21 is prolonged. Therefore,it is preferable that the substrate 21 should be thinned not tointerfere with the handling.

In next step (see FIG. 2B), the substrate 21 is etched by using thesolder resist layer 22 as a mask, and thus recesses 21 x of several tensμm (e.g., 30 μm) depth are formed. An amount of projection of theterminal 24 from the solder resist layer 22 is decided depending upon adepth of the recess 21 x.

Then, in next step (see FIG. 2C), the solder is pasted by theelectroplating while using the solder resist layer 22 as a mask, andthus a solder layer 23 of 2 to 7 μm thickness, for example, is formed onsurfaces of the recesses 21 x. This solder layer 23 acts as an etchingstopper when the substrate 21 is removed by the etching in the laterstep. In this case, tin (Sn), for example, may be plated instead of thesolder layer 23.

After the solder layers 23 are formed, the surface of the solder resistlayer 22 is made rough by applying the plasma process (dry etching).This plasma process is not indispensable, but preferably the plasmaprocess should be applied to ensure sufficiently adhesiveness of the dryfilm or the plating layer used in the later step.

In next step (see FIG. 2D), the terminals 24 are formed by filling acopper in the opening portions 22 a in the solder resist layer 22 bymeans of the electroplating of copper. Then, a seed layer (not shown) isformed on the solder resist layer 22 and the terminals 24 by theelectroless plating of copper.

In next step (see FIG. 2E), a dry film (photosensitive resist film) 25is pasted over the substrate 21. The dry film 25 is exposed by using apredetermined exposure mask (not shown), and then opening portions 25 aare formed in the dry film 25 by applying the developing process. Theseopening portions 25 a are used to form the wirings 26 in next step.

In next step (see FIG. 2F), a copper is filled in the opening portions25 a in the dry film 25 by the electroplating of copper, and thus thewirings 26 are formed. Then, in next step (see FIG. 2G), the dry film 25is removed by a removing liquid. Then, the wirings 26 are separatedelectrically by removing the exposed seed layer by means of the etching.

In next step (see FIG. 2H), the semiconductor chip 27 is flip-chipbonded to the wirings 26. A thickness of the semiconductor chip 27 isthinned to 150 μm or less (preferably almost 50 μm), for example. Theconnection electrodes are provided to edge portions of a device formingsurface (lower side in FIG. 2H). Then, the bumps (e.g., Au stud bumps)28 are formed on the connection electrodes (lower side in FIG. 2H), andthe semiconductor chip 27 is connected electrically to the wirings 26via the bumps 28.

In next step (see FIG. 2I), the underfill 29 is filled between thesemiconductor chip 27 and the substrate 21 (the solder resist layer 22and the wirings 26). As the underfill 29, an epoxy resin, for example,can be employed. It is preferable that a coefficient of thermalexpansion of the underfill 29 should be adjusted to the midway of acoefficient of thermal expansion of the semiconductor chip 27 and acoefficient of thermal expansion of the solder resist layer 22 by mixingthe filler such as silica, for example, with the underfill 29.

In next step (see FIG. 2J), the insulating resin layer 30 is formed bypasting a film-like epoxy resin on the substrate 1 to cover thesemiconductor chip 27. Then, the epoxy resin constituting the insulatingresin layer 30 is cured. Instead of the pasting of the film-like epoxyresin, the insulating resin layer 30 may be formed by coating the epoxyresin. Also, a polyimide resin or other insulating resin may be employedin place of the epoxy resin.

In next step (see FIG. 2K), opening portions 30 a from which the wiring26 is exposed are formed by opening holes to process the insulatingresin layer 30 by means of the carbon dioxide (CO₂) laser, or the like.A diameter of the opening portion 30 a is 100 μm, for example.

In next step (see FIG. 2L), the contact vias 31 are formed by filling acopper in the opening portions 30 a by the electroplating. In this case,as shown in FIG. 2L, top portions of the contact vias 31 are formed torise slightly above the insulating resin layer 30 (e.g., about 30 μm).Then, a Ni—Au plating layer (not shown) of several μm thickness isformed on the top portions of the contact vias 31 by plating Ni (nickel)and Au (gold) sequentially by means of the electroplating.

A plurality of substrates 21 the unit of which is formed in this mannerare prepared. Then, in next step (see FIG. 2M), two sheets of substrates21 are arranged to oppose the semiconductor chip mounting surface toeach other, and then bonded to put the insulating layer 11 between them.An anisotropic conductive film (ACF) is used as the insulating layer 11,and the units 10 formed on the substrate 21 are bonded by applying thepressure by means of the press machine. At that time, a portion of theanisotropic conductive film between the opposing contact vias 31 ispressurized strongly to show conductivity in the thickness direction (Zdirection), and thus the contact vias 31 are connected electrically toeach other. In the following, two units 10 bonded in this manner arecalled a pair unit.

Here, in the present embodiment, the anisotropic conductive film isemployed as the insulating layer 11. But the insulating layer 11 may beformed by filling an insulating resin between the units 10, or the like,after the mutually opposing contact vias 31 of two units 10 are bondedby the solder, or the like.

In next step (see FIG. 2N), the substrate 21 is removed from the unit 10by the etching. In the present embodiment, since the copper plate isemployed as the substrate 21, an iron (III) chloride aqueous solution, acopper (II) chloride aqueous solution, or an ammonium peroxodisulfateaqueous solution, for example, is employed as an etchant. In this case,because end surfaces of the terminals 24 are covered with the solderlayer 23, the etching of the terminals 24 can be prevented.

In next step (see FIG. 2O), a plurality of pair units are stacked to putthe insulating layer 11 between them. In the present embodiment, theterminals 24 adjacent in the vertical direction are connectedelectrically to each other by employing the anisotropic conductive filmas the insulating layer 11. But the insulating layer 11 may be formed byfilling the insulating resin between the pair units, or the like, afterthe terminals 24 are bonded by the solder, or the like.

A stacked structural body 1 a is formed by stacking a plurality of units10 in this manner, and then this stacked structural body 1 a is cut intothe individual electronic parts packaging structure 1. Accordingly, theelectronic parts packaging structure 1 shown in FIG. 1 in the presentembodiment is completed.

According to the manufacturing method of the present embodiment, thesolder resist layer 22, the insulating resin layer 30, etc. aresupported by the substrate 21 until two units 10 are bonded to form thepair unit. Therefore, the handling is facilitated. Also, according tothe present embodiment, the electronic parts packaging structure(semiconductor device) 1 is manufactured by removing the substrate 21after the formation of the pair unit and then stacking a plurality ofpair units. As a result, the thickness can be reduced rather than theelectronic parts packaging structure having the supporting substrate inthe prior art, and thus a much higher mounting density can be attained.

In addition, in the electronic parts packaging structure 1 manufacturedby the manufacturing method of the present embodiment, the arrangementof the solder resist layer 22, the semiconductor chip 27, the wirings26, the terminals 24, the contact vias 31, etc. is verticallysymmetrical between the units 10 adjacent in the vertical direction.Therefore, directions of the warp due to the difference in thecoefficients of thermal expansion among the semiconductor chip 27, theinsulating resin layer 30, the wirings (metal films) 26, and the likecome opposite in the units 10 adjacent vertically. As a result, such asituation can be avoided that the warp is caused in the electronic partspackaging structure 1.

For example, a coefficient of thermal expansion of the copperconstituting the wirings 26, the terminals 24, and the contact vias 31is 16.2 ppm/° C., a coefficient of thermal expansion of thesemiconductor chip 27 (silicon chip) is 3.4 ppm/° C., a coefficient ofthermal expansion of the insulating resin layer 30 (epoxy resin) is 60ppm/° C., a coefficient of thermal expansion of the underfill 29(epoxy-based resin) is 33 ppm/° C., and a coefficient of thermalexpansion of the solder resist layer 22 (epoxy-based resin) is 60 ppm/°C. According to the present embodiment, even in the electronic partspackaging structure (semiconductor device) constructed by the membershaving the different coefficient of thermal expansion respectively, awarp is reduced extremely small and yield of the product becomes high.

In the above embodiment, the stacked structural body la is formed bybonding two sheets of units 10 to obtain the pair unit in the step shownin FIG. 2M, and then by removing the substrate 21 in the step shown inFIG. 2N, and then by stacking a plurality of pair units in the stepshown in FIG. 2O. In this event, after the step shown in FIG. 2L, asshown in FIG. 3, the substrate may be removed from the unit 10 and then,as shown in FIG. 2O, the direction of a plurality of units 10 may bechanged alternately and the units 10 may be stacked and bonded to putthe insulating layer 11 between them.

Also, in the present embodiment, the case where the semiconductor chip27 is mounted to direct its device forming surface toward the substrate21 (so-called face down) is explained. But the invention can be appliedto the case where the semiconductor chip 27 is mounted to direct itsdevice forming surface toward the opposite side to the substrate 21 andis connected electrically to the wirings by the wire bonding (so-calledface up).

(Second Embodiment)

FIG. 4 is a sectional view showing a method of manufacturing anelectronic parts packaging structure according to a second embodiment ofthe present invention, and FIG. 5 is a schematic plan view (generalview) showing the same. In FIG. 4, the same reference symbols areaffixed to the same constituent parts in FIG. 2N.

A difference of the present embodiment from the first embodiment is thatan edge portion is left like a frame when the substrate 21 is removed bythe etching. Since other configurations are basically similar to thefirst embodiment, explanation of redundant portions will be omittedherein.

In the first embodiment, in step shown in FIG. 2N, the substrate 21 isremoved completely from the unit 10. As described above, since aplurality of units 10 are formed at the same time while using a sheet ofsubstrate 21 in the first embodiment, it may be considered that,depending on the number of the units 10 formed simultaneously, the unit10 lacks the rigidity to interfere with its handling after the substrate21 is removed.

For this reason, in the second embodiment, as shown in FIG. 4 and FIG.5, when the substrate is etched, a metal film (an edge portion of thesubstrate 21) 21 a is left like a frame along an outer edge by thephotolithography method.

Accordingly, such an advantage can be achieved that a deflection inhandling can be suppressed and the handling can be made easy. In thiscase, the frame-like metal film 21 a is cut off and removed when thesubstrate 21 is separated into individual units 10.

(Third Embodiment)

FIGS. 6A and 6B are sectional views showing a method of manufacturing anelectronic parts packaging structure according to a third embodiment ofthe present invention.

A difference of the present embodiment from the first embodiment is thatthe solder resist layer 22 is also formed on the back surface (surfaceopposite to the semiconductor chip mounting surface) of the substrate21. Since other configurations are basically similar to the firstembodiment, explanation of redundant portions will be omitted herein.

In the present embodiment, as shown in FIG. 6A, the solder resist layer22 is formed on both surfaces of the substrate 21. Then, like the firstembodiment, as shown in FIG. 6B, the terminals 24 and the wirings 26 areformed and the semiconductor chip 27 is mounted on the wirings 26. Then,the underfill 29 is filled between the semiconductor chip 27 and thewirings 26 and the solder resist layer 22, then the insulating resinlayer 30 for covering the semiconductor chip 27 is formed, and then thecontact vias 31 are formed.

Then, as shown in FIG. 2M, two substrates 21 on which the unit 10 isformed respectively are arranged to oppose the semiconductor chipmounting surface to each other, and then bonded to put the insulatinglayer 11 between them. Then, the solder resist layer 22 formed on theback surface side is removed by the mechanical polishing or the plasmaetching. Thus, the pair unit is formed in this manner. Then, as shown inFIG. 2N, the substrates 21 are removed by the etching. Then, as shown inFIG. 2O, a plurality of pair units are stacked and bonded to put theinsulating layer 11 between them.

In the case where the solder resist layer 22 is formed on one surface ofthe substrate 21 made of copper like the first embodiment, when the postbaking is applied at a temperature of 150 to 200° C., in some cases thesubstrate 21 is warped due to a difference in the coefficient of thermalexpansion between the substrate 21 and the solder resist layer 22 tointerfere with the handling. According to the experiment made by theinventors of this application, it has been confirmed that, when awafer-shaped copper plate having a diameter of 150 mm and a thickness of0.3 mm is used as the substrate 21 and then the solder resist layer 22of 25 μm thickness is formed only on one-side surface of the substrate21, a warp of about 6 mm occurs after the post baking. In contrast, likethe present embodiment, in case the solder resist layer 22 is formed onboth surfaces of the substrate 21, a warp seldom occurs. It isunderstood from this fact that preferably the solder resist layer 22should also be formed on the back surface side of the substrate 21.

The material of the layer formed on the back surface side of thesubstrate 21 is not particularly limited if its coefficient of thermalexpansion is close to that of the solder resist layer formed on thefront surface side.

(Fourth Embodiment)

FIG. 7 is a sectional view showing an electronic parts packagingstructure according to a fourth embodiment of the present invention.

An electronic parts packaging structure (semiconductor device) 51 of thepresent embodiment has a structure that plural (four in FIG. 7) sheet(thin film)-like units 60 are stacked to put an insulating layer 61between them. Each unit 60 is constructed by an insulating resin layer(second insulating layer) 80, a semiconductor chip (electronic parts) 77buried in the insulating resin layer 80, a solder resist layer (firstinsulating layer) 72, and wirings 76. A thickness of one unit 60 isabout 200 μm (about 100 to 300 μm), for example, and respective units 60are electrically connected mutually via through electrodes 81(connection portions) that pass through the electronic parts packagingstructure 51 from one surface side to the other surface side. Both endportions of the through electrode 81 are covered with a Ni—Au platinglayer 81 a.

In the electronic parts packaging structure 51 of the presentembodiment, like the first embodiment, the units 60 adjacent in thevertical direction are arranged in the opposite direction mutually. Thatis, arrangement of the solder resist layer 72, the semiconductor chip77, the wirings 76, the insulating resin layer 80, etc. is symmetricalbetween two units 60 adjacent in the vertical direction.

As described above, one unit 60 is constructed by the semiconductor chip77, the solder resist layer 72, the wirings 76, and the insulating resinlayer 80. The solder resist layer 72 is bonded to one surface of theinsulating resin layer 80. The wirings 76 are formed on the surface ofthe solder resist layer 72 of the insulating resin layer 80 side, andare connected electrically to the connection terminals of thesemiconductor chip 77 via bumps 78. An underfill (protection film) 79for protecting the device forming surface of the semiconductor chip 77is filled between the semiconductor chip 77 and the solder resist layer72.

As described above, in the electronic parts packaging structure 51 ofthe present embodiment, each unit 60 is constructed by the solder resistlayer 72, the semiconductor chip 77, the insulating resin layer 80,etc., and does not have a high strength supporting substrate (in otherwords, a thick substrate) serving as a core. Also, a general strength ofthe packaging structure can be ensured by stacking a plurality of units60. As a result, the electronic parts packaging structure 51 of thepresent embodiment achieves such an effect that a mounting density canbe increased much higher than the prior art, like the first embodiment.

Also, in the electronic parts packaging structure 51 of the presentembodiment, the solder resist layer 72, the semiconductor chip 77, thewirings 76, the insulating resin layer 80, etc. are arrangedsymmetrically between the units 60 adjacent in the vertical direction.Therefore, even though a thermal stress is generated due to a differencein the coefficients of thermal expansion among the semiconductor chip 77and the insulating resin layer 80 and the wirings (the metal films) 76,the warping directions by the thermal stress become opposite in theunits 60 adjacent in the vertical direction. As a result, the thermalstresses can be canceled each other and thus it can be prevented thatthe warp is generated in the electronic parts packaging structure 51.

In addition, the electronic parts packaging structure 51 of the presentembodiment possesses such an advantage that, because an outermostperipheral surface is covered with the solder resist layer 72 made of anacrylic-based resin or an epoxy-based resin whose strength is higherthan an epoxy resin or the like, this packaging structure is hard tobreak down like the first embodiment.

Further, the present embodiment possesses such an advantage that, sincerespective units 60 are connected commonly by the through electrodes 81,the reliability of the electrical connection between respective units 60becomes higher than the first embodiment.

FIGS. 8A and 8N are sectional views showing a method of manufacturingthe electronic parts packaging structure according to the fourthembodiment of the present invention in order of steps. In this case, inFIGS. 8A to 8N, only one unit forming area is shown to simplify theexplanation, but actually a plurality of units 60 are formedsimultaneously on a sheet of substrate 71.

First, in first step (see FIG. 8A), a substrate 71 made of copper (Cu)and having a size of 300 mm×500 mm and a thickness of 0.1 mm, forexample, is prepared. Then, a photosensitive solder resist is coated onone surface of the substrate 71 by the screen printing method, and thusthe solder resist layer 72 of 20 to 30 μm thickness, for example, isformed. Then, a surface of the solder resist layer 72 is made rough byapplying the plasma process (dry etching). Then, a seed layer (notshown) is formed on the solder resist layer 72 by plating a copper bymeans of the electroless plating. The plasma process is notindispensable, but preferably this plasma process should be applied toensure sufficiently adhesiveness of the dry film or the plating layerused in the later step.

In next step (see FIG. 8B), a dry film (photosensitive resist film) 75is pasted on an upper side (on the seed layer) of the substrate 71.Then, the dry film 75 is exposed by using a predetermined exposure mask(not shown), and then opening portions 75 a are formed in the dry film75 by applying the developing process. These opening portions 75 a areused to form the wirings 76 in next step.

In next step (see FIG. 8C), the copper is buried in the opening portion75 a in the dry film 75 by the electroplating of copper, and thus thewirings 76 are formed. Then, in next step (see FIG. 8D), the dry film 75is removed by a removing liquid. Then, respective wirings 76 areseparated electrically by removing the exposed seed layer by means ofthe etching.

In next step (see FIG. 8E), the semiconductor chip 77 is flip-chipbonded to the wirings 76. A thickness of this semiconductor chip 77 isreduced thinner than 150 μm (preferably almost 50 μm), for example, andthe connection electrodes are provided to edge portions of the deviceforming surface (lower side in FIG. 8E). Then, the bumps (e.g., Au studbumps) 78 are formed on the connection electrodes (lower side in FIG.8E), and the semiconductor chip 77 is connected electrically to thewirings 76 via the bumps 78.

In next step (see FIG. 8F), the underfill 79 is filled between thesemiconductor chip 77 and the substrate 71 (the solder resist layer 72and the wirings 76). As the underfill 79, an epoxy resin, for example,can be employed. It is preferable that a coefficient of thermalexpansion of the underfill 79 should be adjusted to the midway of acoefficient of thermal expansion of the semiconductor chip 77 and acoefficient of thermal expansion of the solder resist layer 72 by mixingthe filler such as silica, for example, with the underfill 79.

In next step (see FIG. 8G), the insulating resin layer 80 is formed bypasting a film-like epoxy resin on the substrate 71 to cover thesemiconductor chip 77. Then, the epoxy resin constituting the insulatingresin layer 80 is cured. Instead of the pasting of the film-like epoxyresin, the insulating resin layer 80 may be formed by coating the epoxyresin. Also, a polyimide resin or other insulating resin may be employedin place of the epoxy resin. A plurality of substrates 71 on which theunit 60 is formed in this manner respectively are prepared.

Then, in next step (see FIG. 8H), two units 60 are arranged to opposethe semiconductor chip mounting surface to each other, and then bondedtogether to put the insulating layer 61 between them. In the firstembodiment, the anisotropic conductive film (the insulating layer 11 inFIG. 2M) is used to bond two units 10. In the present embodiment, acommon adhesive resin film such as an epoxy resin, or the like is usedas the insulating layer 61 that is used to bond two units 60. In thefollowing, two units 60 bonded in this manner are called the pair unit.

In next step (see FIG. 8I), the substrate 71 is removed by the etchingusing an iron (III) chloride aqueous solution, a copper (II) chlorideaqueous solution, or an ammonium peroxodisulfate aqueous solution, forexample. In this case, the substrate 71 on one surface side of one ofthe pair units, which are stacked in later step, is covered with theresist film such that one substrate 71 is left after the etching.

In next step (see FIG. 8J), plural pair units are stacked to put theinsulating layer 61, which is formed of a common adhesive resin film,between them and then bonded together. In this case, the unit 60 onwhich the substrate 71 is left is set to the lowermost side.

In this manner, a stacked structural body 51 a constructed by stacking aplurality of units 60 and having the substrate 71 on the lowermost sideonly is formed. Then, in next step (see FIG. 8K), through holes 80 areaching the substrate 71 from an upper surface of the stackedstructural body 51 a are formed by the YAG laser. In the presentembodiment, since the copper is filled in the through holes 80 a by theelectroplating as described later, laser irradiation conditions (laserpower, irradiation time, etc.) are set in such a way that the throughholes 80 a reach the substrate 71 but no hole is opened in the substrate71. At this time, since the optimum laser irradiation conditions arechanged depending upon material/thickness of the resin layer 80,thickness of the wirings 76, stacked layer number of the units 60, etc.,such optimum laser irradiation conditions must be derived in advance bythe experiment, or the like. In this case, the through holes 80 a may beformed by the drilling in place of the laser irradiation.

In next step (see FIG. 8L), the copper is filled in the through holes 80a by depositing the copper on the substrate 71 by means of theelectroplating, and thus the through electrodes 81 are formed. At thistime, as shown in FIG. 8L, the copper is plated until top ends of thethrough electrodes 81 are slightly projected from the uppermost solderresist layer 72.

In next step (see FIG. 8M), an etching resist film 82 is formed on thesolder resist layer 72 on the upper side (the side to which the throughelectrodes 81 are projected) of the stacked structural body 51 a toprotect projection portions of the through electrodes 81. Then, thesubstrate 71 on the lower side of the stacked structural body 51 a isremoved by the etching. Then the etching resist film 82 is removed.

In next step (see FIG. 8N), Ni and Au are sequentially plated on theexposed portions of the through electrodes 81, i.e., the upper side andthe lower side of the through electrodes 81 by the electroless plating.Thus, the Ni—Au plating layer 81 a having a thickness of several μm areformed.

Then, the stacked structural body 51 a is cut into individual electronicparts packaging structures 51. Accordingly, the electronic partspackaging structure 51 of the present embodiment shown in FIG. 7 iscompleted.

In the above first embodiment, as shown in FIGS. 2M to 2O, the units 10are connected electrically by using the anisotropic conductive film (theinsulating layer 11). In this case, when the contact vias 31 or theterminals to put the anisotropic conductive film between them aredisplaced, it is impossible to get an enough conductive performance. Incontrast, in the present embodiment, the through holes 80 a are formedafter the stacked structural body 51 a is formed by stacking respectiveunits 60, and then the through electrodes 81 are formed by filling thecopper in the through holes 80 a. Then, the electrical connectionbetween respective units 60 can be obtained by the through electrodes81. Therefore, the present embodiment possesses such an advantage thatthe electrical connection between respective units 60 can be made easierthan the first embodiment and also the electronic parts packagingstructure with high reliability can be manufactured.

In the above fourth embodiment, when the through holes 80 a are formed,these holes do not pass through the substrate 71. But the through holes80 a may be formed to pass through the substrate 71. In such case,respective units 60 may be connected electrically by applying the copperelectroless plating and the copper electroplating sequentially to innerwall surfaces of the through holes 80 a, for example.

Also, in the present invention, as explained in the second embodiment,when the substrate 71 is removed by the etching, its frame portion maybe left like a frame. In addition, as explained in the third embodiment,the solder resist layer may also be formed on the back surface side(lower surface side) of the substrate 71 and then such solder resistlayer may be removed from the back surface side before removing thesubstrate 71.

1. An electronic parts packaging structure constructed by stacking aplurality of sheet-like units in a thickness direction, each of theunits includes a first insulating layer, a wiring formed on one surfaceof the first insulating layer, an electronic parts connected to thewiring, a second insulating layer formed on an one surface side of thefirst insulating layer to cover the electronic parts, and a connectingportion for connecting electrically the wiring and a wiring of otherunit, wherein arrangement of the first insulating layer, the electronicparts, the wiring, and the second insulating layer is symmetricalbetween units adjacent in a thickness direction.
 2. An electronic partspackaging structure according to claim 1, wherein the first insulatinglayer is formed of a solder resist.
 3. An electronic parts packagingstructure according to claim 1, wherein the connecting portion isconstructed by a terminal formed to pass through the first insulatinglayer and bonded to one surface of the wiring, and a contact via formedto pass through the second insulating layer and bonded to other surfaceof the wiring.
 4. An electronic parts packaging structure according toclaim 1, wherein the connecting portion is formed by filling a conductorinto a through hole that passes through respective units.
 5. Anelectronic parts packaging structure according to claim 1, wherein theelectronic parts is a semiconductor chip.
 6. An electronic partspackaging structure according to claim 5, wherein the semiconductor chipis flip-chip bonded to the wiring.
 7. A method of manufacturing anelectronic parts packaging structure, comprising the steps of: preparinga plurality of sheet-like units each of which is constructed by a firstinsulating layer, a wiring formed on one surface of the first insulatinglayer, an electronic parts connected to the wiring, a second insulatinglayer formed on an one surface side of the first insulating layer tocover the electronic parts, and a connecting portion for connectingelectrically the wiring, and stacking mutually the units to arrangedirections of unit adjacent in a thickness direction alternatelyoppositely, and bonding the units such that electronic parts ofrespective units are electrically connected mutually via connectingportions.
 8. A method of manufacturing an electronic parts packagingstructure, according to claim 7, wherein the step of preparing the unitincludes a first step of forming a first insulating film made of aninsulating resin on a substrate, a second step of forming an opening bypatterning the first insulating film, a third step of forming a recessby etching the substrate exposed from the opening, a fourth step offorming a terminal by filling a metal in the opening, a fifth step offorming a wiring, which is connected to the terminal, on the firstinsulating film, a sixth step of bonding an electronic parts onto thewiring, a seventh step of forming a second insulating layer, whichcovers the electronic parts, on the first insulating film, an eighthstep of forming a hole that reaches the wiring from an upper surface ofthe second insulating layer, a ninth step of forming a contact via byfilling a metal in the hole, and a tenth step of removing the substrate.9. A method of manufacturing an electronic parts packaging structure,according to claim 8, wherein, after the ninth step, two units arebonded to oppose a surface on which the electronic parts is mounted toeach other, and then the substrate is removed by executing the tenthstep.
 10. A method of manufacturing an electronic parts packagingstructure, according to claim 8, wherein, in the tenth step, an edgeportion of the substrate is left like a frame and then the frame-likeportion is cut off and removed after respective units are bonded.
 11. Amethod of manufacturing an electronic parts packaging structure,according to claim 8, wherein, in the first step, a third insulatinglayer is formed on a lower surface of the substrate, and the thirdinsulating layer is removed during a time from an end of the ninth stepto a start of the tenth step.
 12. A method of manufacturing anelectronic parts packaging structure, comprising: a step of forming aplurality of sheet-like units each of which is constructed by a firstinsulating layer, a wiring formed on one surface of the first insulatinglayer, an electronic parts connected to the wiring, and a secondinsulating layer formed on an one surface side of the first insulatinglayer to cover the electronic parts; a step of forming a stackedstructural body by stacking the plurality of units to arrange directionsof unit adjacent in a thickness direction alternately oppositely; a stepof forming a through hole, which passes through the first insulatinglayer, the wiring, and the second insulating layer of respective units,in the stacked structural body; and a step of forming a connectingportion, which connects electrically wirings of respective units, byfilling a conductor in the through hole.
 13. A method of manufacturingan electronic parts packaging structure, according to claim 12, whereinthe step of forming the units includes a step of forming a firstinsulating layer made of an insulating resin on a substrate, a step offorming a wiring on the first insulating layer, a step of bonding anelectronic parts onto the wiring, and a step of forming a secondinsulating layer, which covers the electronic parts, on the firstinsulating layer.
 14. A method of manufacturing an electronic partspackaging structure, according to claim 13, wherein the stackedstructural body is formed by executing sequentially a pair unit formingstep of forming a pair unit by bonding two unit each having thesubstrate to oppose a surface on which the electronic parts is mountedto each other, a substrate removing step of removing the substrate fromthe pair unit, and a stacking step of stacking a plurality of pairunits.
 15. A method of manufacturing an electronic parts packagingstructure, according to claim 14, wherein, in the substrate removingstep, the substrate on one surface side of only one pair unit out of theplurality of pair units is not removed to leave, in the stacking step,the stacked structural body is formed by stacking other pair unit on thepair unit having the substrate, and the connection portion is formed bydepositing a metal on the substrate by a plating method, after thethrough hole reaching the substrate from an upper surface of the stackedstructural body is formed.
 16. A method of manufacturing an electronicparts packaging structure, according to claim 12, wherein the throughhole is formed by a laser.
 17. A method of manufacturing an electronicparts packaging structure, according to claim 12, wherein the throughhole is formed by a drill.